Toy Gun With Pneumatic to Hydraulic Pressure Magnifier

ABSTRACT

A toy gun includes a hydraulic cylinder, a nozzle from which water from the hydraulic cylinder can be expelled, and a hydraulic piston movable in the hydraulic cylinder. The hydraulic cylinder is of a certain surface area. A pneumatic piston is movable in a pneumatic cylinder and is connected to the hydraulic piston. The pneumatic piston has a surface area that is larger than that of the hydraulic piston. Upon triggering, compressed air is delivered to the pneumatic cylinder and pressure induced in the hydraulic cylinder is magnified substantially by the ratio of the two surface areas.

BACKGROUND OF THE INVENTION

The present invention relates to toy guns. The invention moreparticularly, although not exclusively, relates to water-shooting toyguns exploiting pneumatic pressure to propel water from a nozzle.

Due to the compressible nature of gases, compressed air is a relativelyinefficient propellant for firing water from toy guns. For example, aneffective 90 psi of hydraulic pressure behind the nozzle is verydifficult to achieve using stored pneumatic pressure in a toy gun to beoperated by children. However, 50 psi for example is relatively easy toachieve as a stored pneumatic firing pressure.

SUMMARY

Briefly stated, high hydraulic firing pressure is achieved in a toy gunprimed with relatively low pneumatic pressure.

There is disclosed herein a toy gun, comprising:

a hydraulic cylinder;

a nozzle from which water from the hydraulic cylinder can be expelled;

a hydraulic piston movable in the hydraulic cylinder and having ahydraulic surface area;

a pneumatic cylinder;

a pneumatic piston movable in the pneumatic cylinder and connected tothe hydraulic piston, the pneumatic piston having a pneumatic surfacearea that is larger than the hydraulic surface area; and

means for presenting compressed air to the pneumatic cylinder.

Preferably, the toy gun further comprises a reservoir for receivingwater and compressed air above the water, and an inlet valve enablingone-way flow of water from the reservoir to the hydraulic cylinder.

Preferably, the toy gun further comprises a priming pump for compressingthe air above the water in the reservoir.

Preferably, the toy gun further comprises a fluid switch adapted upontrigger-activation to release compressed air from the reservoir to thepneumatic cylinder.

Preferably, the toy gun further comprises a conduit extending betweenthe priming pump and the reservoir, and wherein the fluid switchcommunicates air from a conduit to the pneumatic cylinder.

Preferably, the toy gun further comprises a trigger acting upon thefluid switch.

Preferably, the toy gun further comprises a nozzle valve activated bythe trigger.

Preferably, the pneumatic piston is linked or connected to the hydraulicpiston by a connecting rod.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred form of the present invention will now be described by wayof example with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic cross-sectional elevation of parts of a toy gun ina pre-priming configuration;

FIG. 2 is a similar schematic cross-sectional elevation of the sameparts at the commencement of priming;

FIG. 3 is a similar schematic cross-sectional elevation of the sameparts at a commencement of firing configuration;

FIG. 4 is a similar schematic cross-sectional elevation of the sameparts at a completion of firing configuration;

FIG. 5 is a similar schematic cross-sectional elevation of the sameparts in a post-firing configuration;

FIG. 6 is a similar schematic cross-sectional elevation of the sameparts at a trigger-released post-firing configuration; and

FIG. 7 is a similar schematic cross-sectional elevation of the sameparts in a partially water-depleted condition ready for re-priming.

DETAILED DESCRIPTION

In the accompanying drawings there is depicted schematically theinternal components 10 of a toy gun.

A reservoir 11 is sealed by a cap via which water can be replenished.Extending upwardly into the reservoir 11 is a riser tube 18. The risertube 18 extends almost to the top of the reservoir 11 so that its exitis above water level. The riser tube 18 is connected to a junction 17. Apriming conduit 16 extends from the junction 17 to a primer 13. Primer13 comprises a reciprocating handle 14 connected to a priming piston 15which incorporates a one-way valve 43. The one-way valve 43 at thepriming pump prevents backflow of air from the riser tube 16 to thepump.

Also attached to the junction 17 is a fluid switch 20 activated by atrigger 19.

Located beneath the reservoir 11 is a double cylinder 12 comprising asmall diameter hydraulic cylinder 25 and a large diameter pneumaticcylinder 23. A hydraulic piston 24 slides within the hydraulic cylinder25 and is sealed against the internal cylinder wall 25 by an O-ring.Similarly, a pneumatic piston 22 slides within the pneumatic cylinder 23and has an O-ring to seal against the internal cylinder wall of thepneumatic cylinder 23. Pistons 22 and 24 are fixed to one another by arigid connecting rod 26. The surface area of the hydraulic piston 24 issmaller than the surface area of the pneumatic piston 22.

A firing conduit 21 extends between the fluid switch 20 and thepneumatic cylinder 23.

At the front of the hydraulic cylinder 25 there is a hydraulic firingchamber 30. A nozzle 31 extends from the hydraulic firing chamber 30 toopen space.

Immediately behind the nozzle 31 is a nozzle valve 32 from which thereextends a firing rod 28. The firing rod 28 is sealed through an apertureof the hydraulic firing chamber 30 and biased into the closedconfiguration by a nozzle valve return spring 33.

The firing rod 28 has a stopper 40 at its exposed tail end.

The fluid switch 20 comprises a manifold casing having a manifold rod 34extending longitudinally through it. Attached to the manifold rod 34 isa trigger 19. A trigger return spring 35 biases the trigger to theconfiguration depicted in FIG. 1.

Attached to the trigger 19 is a pull rod 41 having at its distal end acatch 27 through which the firing rod 28 extends.

The manifold rod 34 is sealed into the manifold by a pair of O-rings 37and 38. These O-rings are fixed with respect to the manifold casing andthe manifold rod 34 slides with respect to the O-rings. The manifold rod34 has a circumferential or annular recess 39.

The air gap between manifold rod 34 and the fluid switch (manifold)casing forms the pneumatic exhaust port 36.

In the drawings, the letter “W” represents water or other hydraulicliquid and a letter “A” represents pneumatic gas such as air. Forconvenience, the words “water” and “air” are used.

In use, water is poured into the reservoir 11 and the cap seals thereservoir 11. The handle 14 of the priming pump 13 is reciprocated tobuild up pneumatic pressure in the priming conduit 16, junction 17,riser tube 18 and in the air above the water in the reservoir 11.

Hydraulic pressure in the water of the reservoir rises accordingly. Asthe inlet valve 29 is a one-way valve, water has flowed from thereservoir 11 into the hydraulic firing chamber 30 and into the hydrauliccylinder 25 ahead of the hydraulic piston 24. The air trapped betweenpiston 22 and conduit 21 will be vented to atmosphere through exhaustport 36 via the gap between the O-ring 37 and the annular recess 39 inthe manifold rod 34. The nozzle valve 32 is closed and continuedreciprocation of handle 14 builds up hydraulic and pneumatic pressure inthe system.

When trigger 19 is activated, it moves past the position of FIG. 2 tothe position shown in FIG. 3. The catch 27 of the pull rod 28 pullsagainst the stopper 40. Accordingly, the firing rod 28 opens the nozzlevalve 32 against the return spring 33. At the same time, the annularrecess 39 forms a flow channel around the O-ring 38 so that thepressurised air at the junction 17 passes rapidly through the firingconduit 21 into the pneumatic cylinder 23.

If the pneumatic pressure behind the piston 22 is say 50 psi, the ratioof the diameter of pistons 22 and 24 will produce a correspondinglyincreased hydraulic pressure in the water of hydraulic cylinder 25. Suchpressure might be around 90 psi. The connecting rod applies an equal andopposite force between the pistons. As the movement is dynamic innature, there will of course be some inefficiency due to slightfrictional and leakage losses when the nozzle is opened. The net forceon the connecting rod 26 is to the left. As a result, both pistons 22and 24 move in unison to the left to cause a rapid jet of water throughthe nozzle 31.

When the trigger 19 is released as shown in FIG. 5, the pistons 22 and24 come to rest at the left and nozzle valve 32 is sealed again. Airpressure inside the reservoir 11 will push water into hydraulic firingchamber 30 again via inlet valve 29 as shown in FIG. 6. In thisconfiguration, the manifold rod 34 has moved to the left, so that theannular recess 39 has formed a flow channel around at O-ring 37 so thatair substantially at atmospheric pressure behind the pneumatic piston 22escapes to atmosphere via exhaust port 36.

The system then reverts to the configuration depicted in FIG. 7 whereatthe volume of water remaining in the reservoir 11 has diminished by theamount which escaped via a nozzle 31. The system can continue to beprimed as a solid portion of the manifold rod 34 has sealed againstO-ring 38.

It should be appreciated that modifications and alterations obvious tothose skilled in the art are not to be considered as beyond the scope ofthe present invention.

1. A toy gun, comprising: a hydraulic cylinder; a nozzle from whichwater from the hydraulic cylinder can be expelled; a hydraulic pistonmovable in the hydraulic cylinder and having a hydraulic surface area; apneumatic cylinder; a pneumatic piston movable in the pneumatic cylinderand connected to the hydraulic piston, the pneumatic piston having apneumatic surface area that is larger than the hydraulic surface area;and means for presenting compressed air to the pneumatic cylinder. 2.The toy gun of claim 1, further comprising a reservoir for receivingwater and compressed air above the water, and an inlet valve enablingone-way flow of water from the reservoir to the hydraulic cylinder. 3.The toy gun of claim 2, further comprising a priming pump forcompressing the air above the water in the reservoir.
 4. The toy gun ofclaim 3, further comprising a fluid switch adapted upontrigger-activation to release compressed air from the reservoir to thepneumatic cylinder.
 5. The toy gun of claim 4, further comprising aconduit extending between the priming pump and the reservoir, andwherein the fluid switch communicates air from a conduit to thepneumatic cylinder.
 6. The toy gun of claim 5, further comprising atrigger acting upon the fluid switch.
 7. The toy gun of claim 1, furthercomprising a nozzle valve activated by the trigger.
 8. The toy gun ofclaim 1, wherein the pneumatic piston is linked or connected to thehydraulic piston by a connecting rod.